There are a number of situations in which a moveable carriage must be aligned over a stationary object by detecting a fiducial mark on the stationary object. One method for detecting the fiducial mark "on the fly" is to incorporate an array of photodetectors on the moveable carriage. If the array is sufficiently large, the fiducial mark will alter the light at one or more of the detectors. By determining the identity of the photodetectors that "fired", the location and size of the fiducial mark can be deduced.
If the light signal is weak, a high gain photodetector must be utilized. Such a detector requires a two stage operational amplifier followed by a current to voltage translator. The area on the chip required for the operational amplifiers limits the density of photodetectors in the array. Hence, it would be advantageous to provide a high gain photodetector that requires less area to construct.
Broadly, it is the object of the present invention to provide an improved photodetector.
It is a further object of the present invention to provide a photodetector that requires less area than prior art photodetectors having the same gain.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.